The present invention relates to seals used in the electrophotographic printing process, particularly in laser printer toner cartridges. The seals prevent the leakage of materials, such as toner, from the cartridges.
In the electrophotographic printing process, an image-forming apparatus, such as a printer, performs selective exposures onto a uniformly charged image carrier to form a latent image. The latent image is made visible by toner, and the toner image is transferred to a recording medium so that the image may be rendered permanent. In such an apparatus, additional toner must be supplied each time it is used up. Not only is this operation for supplying toner inconvenient, but the operator""s hands or clothing may become dirty if they come in contact with the toner. Also, the presence of the toner makes it necessary to periodically perform maintenance on each member of the apparatus. The result is leakage and spillage of toner that is best avoided in the electrophotographic printing apparatus.
FIG. 1 illustrates a conventional process cartridge in which supplying of toner and replacement of parts of an image carrier whose service life is finished are made possible when a user loads the cartridge into the main body of the printing apparatus. Maintenance is made easier since an image carrier (50), a charger (51), a developing unit (developer roll) (52), a cleaning unit (53), and the like, are formed integrally into the cartridge. Cartridges of this type are disclosed, for example, in U.S. Pat. Nos. 3,985,436; 4,500,195; 4,540,268; 4,627,701; 5,995,774; and 6,009,285; all of which are incorporated herein by reference.
In such a process cartridge, the developing unit is provided with a sealing member (55) so that the toner will not leak out from a gap formed between the developer roll (52) and a development frame member (54). The cleaning unit (53) has a sealing member (56) provided in the end portion of the image carrier (50) so that waste toner will not leak out from the gap formed between the end portion of the image carrier (50) and the waste toner well (53a).
Sealing between the developer roll (52), the doctor blade (57), and the developer housing (frame) (54) is difficult because the developer roll is a rotating cylinder immersed in toner for a portion of its revolution and exposed external to the developer unit for the other portion of the cycle. The doctor blade moves in a direction perpendicular to the tangential surface velocity of the developer roller making sealing difficult. A seal must also be made between the doctor blade seal and the lower developer roll seal that extends the length of the developer housing to the other end seal.
One type of the above-mentioned sealing member is formed from foam rubber, felt or the like so that it can be applied onto a container. Another type is formed from a material such as plastic, as a lip portion which slideably contacts process means such as the developer sleeve (52), the frame member (54) or the like so that the seal can be installed into the frame member. With the former sealing member, it is time-consuming to apply the sealing member and automation of attachment is difficult. The latter sealing member has the advantage that attachment is easy. However, the dimensions of the portion where the sealing member comes into close contact with the frame member varies, causing the problem, for example, of the toner leaking from the gap.
A commonly used seal on laser printer toner cartridges incorporates a dynamic seal design consisting of two lip seals in contact with the developer roll and doctor blade that are angled relative to the developer roll surface velocity direction in order to actively push (snowplow) toner back into the developer sump. This seal design requires an internal pocket in the developer housing for retention and support. This pocket can be created in cartridges by attachment of external pieces, such as end caps. These external pieces add additional costs to the toner cartridge and add additional part interfaces that can allow toner leakage if not sealed by an additional means. The additional means of sealing these end cap interfaces is frequently accomplished by the use of a putty substance and/or a wax substance. Application of these substances onto the cartridge is difficult, costly, and they are prone to contaminate other critical areas of the cartridge when mis-installed. This type of seal is described in IBM Technical Disclosure Bulletin, Vol. 33, No. 38, pg. 29 (1990).
U.S. Pat. No. 5,697,021, Watanabe, et al., issued Dec. 9, 1997, describes a sealing means for a toner cartridge formed from a soft plastic material. The U-shaped seal mounts on the end of the cartridge (see FIG. 11 of the Watanabe, et al. patent) and may include an extended lip which scrapes toner off the doctor blade and back into the toner sump (see FIG. 6 of the Watanabe, et al. patent). These structures do not utilize ridges on the inside face of the seal to guide toner back into the cartridge. See also, U.S. Pat. No. 5,475,467, Watanabe, et al., issued Dec. 12, 1995.
U.S. Pat. No. 5,550,617, Odagawa, et al., issued Aug. 27, 1996, describes a process cartridge for an electrophotographic printer, the elements of which are made from a synthetic resin, making recycling of the cartridge components easy and effective. End-seals made from the synthetic resin are disclosed; they may be integral with the blade members or the blade supports. Again, there is no discussion of placing ridges on the inside face of the seal to guide toner back into the cartridge (see FIGS. 8-11 of the Odagawa, et al. patent).
U.S. Pat. No. 5,502,547, Shirai, issued Mar. 26, 1996, describes sealing members for use in a toner cartridge which comprise a resin face plate having a tongue and groove means on one face for attaching to the printer, and a foam portion on the other face to form the seal (see FIG. 8 of the Shirai patent). The key to this patent is that the seals can be recycled. Again, there is no discussion of using ridges on the interior face of the seal.
The present invention relates to a sealing member for an image-forming apparatus including a frame member, a rotary member and a blade member, said sealing member comprising:
a rotary seal portion for sealing a space formed between the frame member and the rotary member, said rotary seal portion incorporating ridges set at an angle across its face adjacent to the surface of said rotary member;
a blade seal portion for sealing a space formed between the frame member and the blade member; and
a means for biasing said sealing member toward the surface of said rotary member and the blade member.
The seal member is typically made from a flexible, low modulus material, such as urethane or artificial rubber. It is generally used to prevent the leakage of toner from an electrophotographic process cartridge; in that instance, the rotary member is generally a developer roll and the blade member is a doctor blade. The means for biasing the seal can be, for example, a cantilever beam, cantilever springs or a foam strip.
The present invention also encompasses a process cartridge detachably mountable to an image-forming apparatus, said process cartridge comprising:
a frame member;
a rotary member mounted on said frame member, said rotary member constituting process means;
a blade member elastically contacting said rotary member; and
a sealing member comprising
a rotary seal portion for sealing a space formed between the frame member and the rotary member, said rotary seal portion incorporating ridges set at an angle across its face adjacent to the surface of said rotary member;
a blade seal portion for sealing a space formed between the frame member and the blade member; and
a means for biasing said sealing member toward the surface of rotary member and the blade member.